There is no admission that the background art disclosed in this section legally constitutes prior art.
Assay tests have been employed to analyze test samples such as urine samples to determine whether or not they contain substances such as HCG indicating pregnancy, drugs of abuse, or other.
For example, reference may be made to the following United States patents, each of which is incorporated herein by reference:
U.S. PAT. NO.INVENTORISSUE DATE4,033,723Givner, et al.Jul. 5, 19774,123,509Banik, et al.Oct. 31, 19784,348,207CappelSep. 7, 19824,450,239ChattertonMay 22, 19844,700,711CarlsonOct, 20, 19875,182,216Clayton, et al.Jan, 29, 19935,580,794Allen, et al.Dec. 3, 19965,656,503May, et al.Aug. 12, 19975,786,220Pronovost, et al.Jul. 28, 19985,873,546Allen, et al.Nov. 17, 19986,063,026Schauss, et al.May. 16, 20006,150,178Cesarczyk, et al.Nov. 21, 20006,235,241B1Catt, et al.May 22, 2001
Test strips, as disclosed in one or more of the foregoing patents, are employed to receive a test sample such as a urine sample for performing an assay test. For example, a pregnancy test strip has been used to collect a urine sample to react with a reagent to produce a visible line such as a line having a pink/purple color. It is sometimes difficult to make a subjective determination as to the intensity of the color of the line relative to a comparison line. Thus, false positive indications are sometimes possible.
In an attempt to help interpret the results of such assay test, the U.S. Pat. No. 6,235,241B1 discloses a test strip disposed within a casing or housing, and uses a method of illuminating using diffusers through a test strip to help the user to interpret the results of a test. Light is sensed on the other side of the test strip by detecting light shining through the test strip. However, such a method is complex in its use, and thus relatively expensive to use.
For the purpose of providing a relatively inexpensive assay test device, which can be for single use only, as disclosed in U.S. Pat. Nos. 5,580,794 and 5,873,546, there is disclosed a method using a test membrane containing a reagent, and receiving a liquid test sample thereon. The presence of movement of the sample liquid is detected and activates the device electrically. The results of the chemical reaction of the reagent with the test sample is then sensed. In this regard, as the liquid sample moves along the test strip, the reaction is occurring and the results are sensed once the liquid reaches a certain point along the strip. Alternatively, another method is disclosed where the device may be activated electrically by closing a switch when it is removed from its pouch, and the reaction results are sensed after a specified time.
However, when the former method is used, the reaction time may be dependent on the length of time it takes for the movement of the liquid sample along the membrane. Thus, the reaction time may not be precisely controlled and repeatable, and thus accuracy may be adversely affected.
When the latter method of sensing the reaction results sometime after initially turning on the device, following a time delay, the reaction time is even less precisely controlled. There is little or no control over when the sample is first introduced to the membrane following the activation of the device, and thus the processing time could vary widely.
It is, of course, important to provide sufficient time to process the reaction. Either permitting the reaction process time to be determined by the propagation time of the sample, or by allowing the sample to be introduced at any time (even shortly before the reaction is analyzed), does not provide adequate control for the proper analysis of the reaction.
Therefore, it would he highly desirable to have a new and improved testing method, which is relatively more accurate in the determination of the test results, while at the same time being relatively inexpensive to use. Thus, such a method may, if desired, be employed for a single use, and yet be relatively accurate in its use.